My experience with hundreds of people during the last sixteen years shows that the chances for rebuilding trust depend on some basic behaviors on the part of the person who had an affair:

being willing to answer your questions
hanging in while you deal with the understandable emotions
demonstrating a commitment to the relationship by severing contact with the other person

All this is aimed at strengthening the bond that has been broken. It demonstrates a willingness to handle problems in a responsible way instead of trying to bury them, avoid them, or hope they go away. There are no shortcuts; the only way through this situation is to face it head on and deal with it. Even then, it will be difficult for everyone.

Certainly, no one (either the one who had an affair or their partner) wants to drag this out; it's so painful and uncomfortable that everybody wants it to be over quickly, but it can't be rushed. So unless both people are willing to commit to honesty and to investing the time and energy necessary to deal with all this, they're unlikely to make it together; or if they do, the emotional distance from the lack of commitment to doing what's necessary leads to a deadened, meaningless marriage.

But there is hope that by actively working together, you can come through this with a stronger relationship and greater trust than you had before. A crisis like this provides a chance to "get it right"—something most of us didn't really do in the first place when we had a kind of "blind trust" and just assumed everything would work out all right.

I can honestly say that I would never have chosen to go through all this in order to get to the kind of relationship we have now; but since it did happen, we learned from it and devoted ourselves to developing a strong bond based on complete honesty and a commitment to fairness and equality. Because of this, our trust is stronger than it ever was before the affairs.